Waves of nationalism come and go. If you've got a big enough population, you can easily promote your native language as superior to others because it can express X, Y, and Z beautiful concepts easily while filthy foreign languages can't.
There were a few campaigns where various western countries tried promoting their alphabets over native writing systems. Some succeeded (e.g. Vietnamese) and many others failed. Trying to completely change the language is an even bigger stretch. Places like India have a long history of English, but few Indian people speak pure British English. Most will throw a mix of perfectly pronounced English words in the middle of a sea of their local language. English doesn't have a clear path to domination despite it being spoken by so many people.
Indian English is very similar to the British English of shortly before India gained independence from the British Empire (1947). That means it often sounds formal or old-fashioned. The reason for this is because linguistic change occurs almost entirely in places where that language is the first language, and English is only ever a second or subsequent language in India.
There has been some synchronisation with other English locales due to the effects of globalisation, but not a great deal. Beyond that, it does have some deviations from British English as it was in the days of the Empire, mostly due to grammatical misunderstandings becoming common and thus standard, or linguistic patterns from local languages making their way into English; the two examples that spring most immediately to my mind (as an Australian currently in Hyderabad): “very less” instead of “very little”, and a gratuitous “only” suffix where other dialects would either omit it or place it earlier in a sentence.
Concerning fiblye’s point: in cities, you’ll hear a fair smattering of English words when people are speaking their local languages. In rural areas this happens much less.
There were a few campaigns where various western countries tried promoting their alphabets over native writing systems. Some succeeded (e.g. Vietnamese) and many others failed. Trying to completely change the language is an even bigger stretch. Places like India have a long history of English, but few Indian people speak pure British English. Most will throw a mix of perfectly pronounced English words in the middle of a sea of their local language. English doesn't have a clear path to domination despite it being spoken by so many people.